ARM: Allow SMP kernels to boot on UP systems

UP systems do not implement all the instructions that SMP systems have,
so in order to boot a SMP kernel on a UP system, we need to rewrite
parts of the kernel.

Do this using an 'alternatives' scheme, where the kernel code and data
is modified prior to initialization to replace the SMP instructions,
thereby rendering the problematical code ineffectual.  We use the linker
to generate a list of 32-bit word locations and their replacement values,
and run through these replacements when we detect a UP system.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 10 deletions

diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
index 37c8157e116e..e8ea1a071f43 100644
--- a/arch/arm/mm/cache-v7.S
+++ b/arch/arm/mm/cache-v7.S
@@ -91,11 +91,8 @@ ENTRY(v7_flush_kern_cache_all)
  THUMB( stmfd   sp!, {r4-r7, r9-r11, lr}        )
         bl      v7_flush_dcache_all
         mov     r0, #0
-#ifdef CONFIG_SMP
-        mcr     p15, 0, r0, c7, c1, 0           @ invalidate I-cache inner shareable
-#else
-        mcr     p15, 0, r0, c7, c5, 0           @ I+BTB cache invalidate
-#endif
+        ALT_SMP(mcr     p15, 0, r0, c7, c1, 0)  @ invalidate I-cache inner shareable
+        ALT_UP(mcr      p15, 0, r0, c7, c5, 0)  @ I+BTB cache invalidate
  ARM(   ldmfd   sp!, {r4-r5, r7, r9-r11, lr}    )
  THUMB( ldmfd   sp!, {r4-r7, r9-r11, lr}        )
         mov     pc, lr
@@ -171,11 +168,8 @@ ENTRY(v7_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mov     r0, #0
-#ifdef CONFIG_SMP
-        mcr     p15, 0, r0, c7, c1, 6           @ invalidate BTB Inner Shareable
-#else
-        mcr     p15, 0, r0, c7, c5, 6           @ invalidate BTB
-#endif
+        ALT_SMP(mcr     p15, 0, r0, c7, c1, 6)  @ invalidate BTB Inner Shareable
+        ALT_UP(mcr      p15, 0, r0, c7, c5, 6)  @ invalidate BTB
         dsb
         isb
         mov     pc, lr